diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 58614302..b908048f 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1345,6 +1345,7 @@ RMarkdown:
   type: markup
   lexer: Text only
   wrap: true
+  ace_mode: markdown
   primary_extension: .rmd
   extensions:
   - .Rmd